September 19, 2025 — Beneath the surface of the Chesapeake Bay, a quiet but significant transformation is taking place. Eelgrass, long a foundational seagrass species supporting fish, crabs, and other marine life, is declining in parts of the Bay. Its warmer-water relative, widgeon grass, is expanding in its place.
Researchers from William & Mary’s Batten School of Coastal Marine Sciences and the Virginia Institute of Marine Science (VIMS) conducted a study, and say this shift could have major ecological consequences and potentially affect fisheries and the health of the Bay itself.
What’s Happening Underwater
Eelgrass and widgeon grass may look similar at first glance, but their differences are significant. Lauren Alvaro, a marine ecologist who conducted extensive fieldwork for the study, explains: “Not all seagrasses are created equal. Eelgrass has broader leaves like linguine, while widgeon grass is more like angel hair pasta. And those differences affect the types of creatures they support.”
Eelgrass meadows typically support larger animals, such as blue crabs and fish prized by anglers. Widgeon grass, meanwhile, supports smaller animals, and while there may be more individuals per gram of plant material, the overall biomass is lower. In other words, even if the Bay looks full of seagrass, the types and sizes of animals it supports are changing.